Preheat the oven to 375°F and lightly grease a 9x9 inch baking dish.
Cook the egg noodles in a large pot of salted boiling water until just tender, then drain and set aside.
In a large bowl, stir together the cream of mushroom soup, milk, salt, and black pepper until smooth.
Add the drained tuna, shredded cheddar cheese, and cooked noodles to the bowl. Mix gently until everything is coated.
Transfer the mixture to the prepared baking dish and spread it into an even layer.
In a small bowl, toss the crushed crackers with the melted butter until evenly coated.
Sprinkle the buttered cracker crumbs over the top of the casserole.
Bake for 20 to 25 minutes until the edges bubble and the topping turns golden.